Lee won the 2006 Miss Korea pageant and was the 3rd runner-up in the Miss Universe pageant in 2007. She was named Miss Grand Slam 2007.
In 2008, she made her acting debut in the musical Polaroid which opened at PMC Daehangno Jayu Theater in Hyehwa-dong, Jongno-gu She has since starred in musicals Legally Blonde', playing Elle Woods and Chicago, playing Roxie Hart.
In 2009, Lee starred in her first television series The Partner, playing a femme fatale attorney. She next starred in the romantic comedy series Pasta (2010), playing a Celebrity chef.
In 2011, Lee was cast in her first big screen role in action film, Hit. She also featured in the disaster film Deranged and period comedy I Am a King (2012).
In February 2013, it was confirmed that Lee was in a relationship with South Korean actor and singer Yoon Kye-sang.
In 2016, Lee starred in the comedy drama Please Come Back, Mister. Lee was praised for her chemistry with co-star Oh Yeon-seo, whom she has acted with in her previous project Shine or Go Crazy.
In 2017, Lee played famous gisaeng Jang Nok-su in the historical drama The Rebel. She won critical praise for her portrayal, and won several acting awards. The same year, she featured in crime thriller Heart Blackened and action comedy film The Bros. Lee is set to star next in the comedy film Extreme Job.
Lee performed at the closing ceremony of the 2018 Winter Olympics, where she reinterpreted '춘행무(Chunaengmu)', one of the royal dances of the Joseon dynasty.
After appearing in E J-yong’s ensemble mockumentary Behind the Camera (2013), Lee starred in the gambling film 'Tazza: The Hidden Card (2014), playing a rich widow.